As the needs for the UHD (Ultra High Definition) video increase, the size of a storing medium and the bandwidth of a transfer medium cannot be satisfied based on the current MPEG (Moving Picture Expert Group) technology, which means that a new video coding technology, which is able to code the UHD video, is necessary. To resolve this problem, the HEVC (High Efficiency Video Coding) was standardized in January, 2013.
However, the HEVC can be employed for the sake of a video stream which is currently being provided via the internet, 3G, LTE, etc. The HEVC is able to code the UHD video as well as the FHD (Full High Definition) or HD videos into the form of a HEVC file.
It is expected that the UHD TV will be designed to operate at 4K 30 fts, but the number of pixels which should be processed per second might increase like 4K 60 fps/120 fps, 8K 30 fps/60 fps, . . . , etc.
In order to cost-effectively cope with various resolutions and frame rates due to the changing applications, it needs to provide a video decoder unit which is able to easily carry out the performance, function, etc. which are required by the applications.
For the sake of the above-mentioned applications, a predetermined video processing method may be employed, which can be carried out based on a parallel processing method using a plurality of processing units. In case of the parallel processing method using a plurality of the processing units, a split bitstream may be assigned to each of the processing units, thus carrying out a decoding process.
However, if the above-mentioned parallel processing method is simply employed, a predetermined unbalancing situation may occur between the processing units. Moreover, the efficiency of the bandwidth may be degraded due to such an unbalance. A predetermined disadvantage may occur in terms of the configuration of a hardware.
In particular, if coding units (for example, a tile, a slice, etc.) having different sizes exist in one pixel, the time that the tiles or slices assigned to each processing unit are decoded may differ. For this reason, even though a multi-decoding process is carried out using a plurality of the processing units, the processing time of each processing unit may differ, which may cause a problem wherein the whole decoding time synchronization may not be carried out, and otherwise it is hard to predict the whole decoding time synchronization, which consequently may result in the increased inefficiency.
Meanwhile, the coding and decoding methods based on the WPP (Wavefront Parallel Processing) method may be proposed for the sake of the parallel decoding method using a plurality of processing units. This method, however, may has a problem wherein in order for the parallel decoding process to be carried out using a plurality of the processing units during the decoding process, a WPP format information should be written in header information of the bitstream during the coding process due to its natural structure in case of the HEVC standardization method which is currently available, whereby the applicable range thereof may be limited.
Moreover, according to the ordinary WPP processing method, except for the above-described unbalancing problem, another problem may occur during a processing order allocation with respect to each processing unit. The outputs should be synchronized based on the unit of the pictures for the sake of a normal video playback, whereby the decoding process can be carried out, wherein the outputs are synchronized based on the unit of the pictures. For this reason, a part of the processing units should inevitably standby for the sake of synchronization, whereupon the latency may increase during the decoding process, and the whole decoding time may increase.